1. Field of the Invention
The present invention relates to delay detonators, and more particularly to delay detonators having improved resistance to external shock.
2. Description of the Prior Art
The explosive charges used in trenching operations often are loaded into holes which are close enough to one another that the shock from the detonation of an earlier-fired charge may deleteriously affect a delay detonator positioned in the charge in an adjacent hole to be fired thereafter, with the result that the latter charge may fail to detonate, or detonate incompletely. Such failures are even more prevalent when the shooting is carried out in wet areas, where shock transmission is enhanced. In many cases, detonators which have failed to function properly owing to explosive shock effects in wet areas, sometimes referred to in the art as the "water hammer" effect, appear to have been crushed, suggesting that reinforcement of the shell wall might alleviate the problem. Such reinforcement would be costly, however, and could reduce the detonator's output.